The present invention is related to providing a method for controlling a temperature detecting circuit of an automatic bread baking machine for detecting the change of the temperature according to the advancement of the bread baking procedure, for example kneading the ingredients of the bread (the dough), fermenting the dough twice and baking the dough to automatically produce the bread.
A conventional automatic bread baking machine has been two types using a microprocessor provided with a functioning means for converting the analog signal into the digital signal therein and a microprocessor not having said signal conversion function in order to detect the temperature of a bread baking machine. But, in case of using a microprocessor not having said signal conversion function, a temperature detecting circuit and a analog/digital converter are connected to a microprocessor to detect the temperature, said circuit and converter are generally complex and their manufacturing cost is very high. Also, if using a microprocessor having said conversion function, the typical example is as follows;
As shown in FIG. 1, microprocessor 1 is provided with a temperature detecting circuit including thermistor TH1, resistors R1 and R2, condenser C1 and constant voltage zener diode ZD1. Therefore, as the resistance value of thermistor TH1 is varied respective to the temperature change, the voltage applied to input terminal IN of microprocessor 1 is changed to detect the temperature, but even though this machine did not use a expensive analog/digital converter, a microprocessor having the conversion function is more expensive than that not having the conversion function. Due to such factor, manufacturing cost is increased, while if microprocessor 1 is masked according to the determination of the temperature data based on the voltage received at input terminal IN, the temperature data must not change dependent upon the abnormal condition. Also, if a mechanism configuration of the product or the type of a thermistor is to be changed, voltages input according to the temperature change are different from each other. Therefore, the temperature data as to the voltage must be changed, and then a microprocessor must be newly masked again. As a result, the determination of the temperature data in connection with the input voltage following after the development of the new products is required, and much time and cost required for developing the products are needed.
Such a conventional automatic bread baking machine was operated based on the temperature curve graph shown in FIG. 2 to perform the baking of the bread. That is to say, if it firstly executes kneading of the bread ingredients, preliminary fermenting of the dough, secondary fermenting of the dough and then baking of the fermented bread, baking of the bread was performed 2-3 times based on the standard temperature curve L1 or based on the standard temperature curve L1, the high temperature curve L2 and the low temperature curve L3 according to the selection of the baking level by operating the key matrix, but it has been disadvantages that due to the assembling errors of the mechanical parts and the errors of the circuit elements mounted in the automatic bread baking machine, the condition of the bread baking as not operated in uniform while three selections as described above could not satisfy various tastes of the consumer.
The typical example in U.S. Pat. No. 4,538,509 issued to Shin Ojima, You, etc. entitled "AUTOMATIC BREAD BAKING MACHINE". This patent includess a control portin provided with a microprocessor for adjusting the temperature in order by the timing control on the basis of the temperature which at least one sensors mounted into a baking container and a kneading bar detect.